<template>
    <div class="s-canvas" @click="refreshCode">
        <canvas id="s-canvas" :width="contentWidth" :height="contentHeight"></canvas>
    </div>
</template>

<script setup>
import { watch, onMounted } from 'vue';

// 定义 props
const props = defineProps({
    identifyCode: {
        type: String,
        default: '1234'
    },
    fontSizeMin: {
        type: Number,
        default: 20
    },
    fontSizeMax: {
        type: Number,
        default: 40
    },
    backgroundColorMin: {
        type: Number,
        default: 180
    },
    backgroundColorMax: {
        type: Number,
        default: 240
    },
    colorMin: {
        type: Number,
        default: 50
    },
    colorMax: {
        type: Number,
        default: 160
    },
    lineColorMin: {
        type: Number,
        default: 40
    },
    lineColorMax: {
        type: Number,
        default: 180
    },
    dotColorMin: {
        type: Number,
        default: 0
    },
    dotColorMax: {
        type: Number,
        default: 255
    },
    contentWidth: {
        type: Number,
        default: 120
    },
    contentHeight: {
        type: Number,
        default: 40
    }
});

// 定义 emit
const emit = defineEmits(['refresh']);

// 生成随机数
const randomNum = (min, max) => {
    return Math.floor(Math.random() * (max - min) + min);
};

// 生成随机颜色
const randomColor = (min, max) => {
    const r = randomNum(min, max);
    const g = randomNum(min, max);
    const b = randomNum(min, max);
    return `rgb(${r},${g},${b})`;
};

// 绘制验证码
const drawPic = () => {
    const canvas = document.getElementById('s-canvas');
    const ctx = canvas.getContext('2d');
    ctx.textBaseline = 'bottom';
    // 绘制背景
    ctx.fillStyle = randomColor(props.backgroundColorMin, props.backgroundColorMax);
    ctx.fillRect(0, 0, props.contentWidth, props.contentHeight);
    // 绘制文字
    for (let i = 0; i < props.identifyCode.length; i++) {
        drawText(ctx, props.identifyCode[i], i);
    }
    // 绘制干扰线
    drawLine(ctx);
    // 绘制干扰点
    drawDot(ctx);
};

// 绘制文字
const drawText = (ctx, txt, i) => {
    ctx.fillStyle = randomColor(props.colorMin, props.colorMax);
    ctx.font = `${randomNum(props.fontSizeMin, props.fontSizeMax)}px SimHei`;
    const x = (i + 1) * (props.contentWidth / (props.identifyCode.length + 1));
    const y = randomNum(props.fontSizeMax, props.contentHeight - 5);
    const deg = randomNum(-30, 30);
    // 旋转文字
    ctx.translate(x, y);
    ctx.rotate((deg * Math.PI) / 180);
    ctx.fillText(txt, 0, 0);
    ctx.rotate((-deg * Math.PI) / 180);
    ctx.translate(-x, -y);
};

// 绘制干扰线
const drawLine = (ctx) => {
    for (let i = 0; i < 4; i++) {
        ctx.strokeStyle = randomColor(props.lineColorMin, props.lineColorMax);
        ctx.beginPath();
        ctx.moveTo(randomNum(0, props.contentWidth), randomNum(0, props.contentHeight));
        ctx.lineTo(randomNum(0, props.contentWidth), randomNum(0, props.contentHeight));
        ctx.stroke();
    }
};

// 绘制干扰点
const drawDot = (ctx) => {
    for (let i = 0; i < 30; i++) {
        ctx.fillStyle = randomColor(0, 255);
        ctx.beginPath();
        ctx.arc(randomNum(0, props.contentWidth), randomNum(0, props.contentHeight), 1, 0, 2 * Math.PI);
        ctx.fill();
    }
};

// 刷新验证码
const refreshCode = () => {
    emit('refresh');
};

// 监听 identifyCode 变化
watch(() => props.identifyCode, () => {
    drawPic();
});

// 组件挂载时绘制验证码
onMounted(() => {
    drawPic();
});
</script>

<style scoped>
.s-canvas {
    cursor: pointer;
}
</style>